APPLICATION OF THE LAWS OF HYDRAULICS
the following manner. The column of water h is balanced by the
column of kerosene H. The specific weight of water is 1.0 and
that of kerosene is 0.80; it follows that :
and the difference in level will be 0.25/i, equivalent to a column
of water of 0.25/1 X0.8 = 0.2/i.
This experiment may be modified as follows: take a beaker
of water and immerse therein a test-tube filled with kerosene,
until the bottom of the test-tube is even with the surface of the
water, the test-tube being inverted (Fig. 10), and determine the
hydrostatic pressure which it supports. It is evident that at the
level B the pressure exerted by the water upon the kerosene and
the pressure reciprocally exerted by the kerosene upon the water
are equal, because they are in equilibrium.
The pressure of the water per unit of surface in millimeters of
water column is that given by the height h:
-Pwater = h X density of water = AXl = fe mm.
The pressure of the kerosene is measured, first, by the weight